The present invention relates to the field of material handling, and more particularly, to triggering apparatuses for use with material handling apparatuses for particulate solid material, and to material handling apparatuses for use with particulate solid material.
It is not uncommon in a modern factory for a large number of molding or extrusion devices to be present. Typically, such devices utilize plastic resin in particulate solid (powder or pellet) form as a feedstock. To simplify inventory, as well as material handling, particulate solid plastic resin is shipped in bulk to a central storage area in the factory. From the central storage area, a plurality of conduits extend, each conduit terminating at a respective loader dedicated to one of said molding or extrusion devices. Each loader includes a hopper capable of receiving a volume of said resin and in which a vacuum can be formed, to draw said resin from the central storage area, through the conduit and into the hopper. When the hopper has been filled, the vacuum ceases to be drawn, and a discharge port in the base of the hopper opens to discharge the collected resin material into a receptacle disposed beneath the hopper. As the level of the material in the receptacle drops, the discharge port can be closed, so as to permit further resin material to be drawn into the hopper, to repeat the process.
Closure of the discharge port can, of course, be triggered manually, but it is advantageous to automate the process.
A variety of devices are known in the prior art to automatically trigger such closure of the discharge port. Optical-based devices are currently favoured, for reasons of purchase economy and reliability. However, it is possible for the xe2x80x9clensxe2x80x9d portion of such devices to become coated with resin dust, or otherwise soiled, whereupon operation becomes unpredictable. As such, maintenance requirements for triggering apparatus of this type can be substantial.
It is an object of the present invention to provide a trigger apparatus for use with a material port through which a flow of particulate solid material selectively passes, said trigger apparatus being relatively economical and reliable and having lesser maintenance requirements than devices of similar economy and reliability in the prior art.
This object, and others, is met by one aspect of the present invention, a trigger apparatus for use with a material port through which a flow of particulate solid material selectively passes.
The trigger apparatus comprises a trigger body, a bias means and a sensor means.
The trigger body has a first position and a second position and defines a threshold level of said particulate solid material. The trigger body is adapted to be positioned, in use, beneath said material port so as be impinged upon by said flow when at its first position and moved therefrom by said flow to its second position. The trigger body is further adapted, upon accumulation of said particulate solid material from said flow beneath said material port beyond the threshold level, to be restrained as against movement to said first position by said particulate solid material until such time as the particulate solid material recedes to said threshold level.
The bias means is for biasing the trigger body for movement to its first position.
The sensor means is for producing a signal responsive to movement of the trigger body to its first position.
As other aspects of the invention, the trigger body preferably comprises a vane portion which, in use, is impinged upon by said flow, which impingement provides for said movement of the trigger body from its first position to its second position.
As another aspect of the invention, the trigger apparatus preferably further comprises a float portion.
As a further aspect of the invention, in non-flow conditions when said particulate solid material has accumulated from said flow beneath said material port beyond the threshold level, said particulate solid material preferably blocks movement of the float portion, in the course of said movement of the trigger body from its second position to its first position through the agency of the bias means, thereby to provide for said trigger body to be restrained as against movement to said first position by said particulate solid material until such time as the particulate solid material recedes to said threshold level.
A material handling apparatus including the trigger apparatus and for use with particulate solid material is another aspect of the invention.
In addition to the trigger apparatus, the material handling apparatus comprises a loader.
The loader includes a hopper, a discharge cone, an actuator means and a receptacle.
The hopper is for receiving said particulate solid material and has a discharge port at the base thereof.
The discharge cone has an open position, apart from the discharge port, whereat particulate solid material within said hopper can flow through said discharge port, and a closed position, occluding said discharge port, whereat said flow is arrested.
The actuator means is for selectively moving the discharge cone between the open position and the closed position thereof.
The receptacle is positioned beneath said hopper to receive particulate solid material discharged through said discharge port.
The trigger apparatus is used with the loader with the discharge port of said hopper defining the material port, the trigger body being operatively mounted to the loader for movement between its first position and its second position, and the actuator means being adapted to move the discharge cone to the closed position thereof in response to the signal from the sensor means.
Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which is briefly described hereinafter.